Abstract: :
Purpose: To determine whether glucose exposure induces signsof oxidative stress in tissue cultured bovine retinal pericytes,i.e. increased lipid peroxidation and activation of the cellulardefence system against oxidative stress. Pericytes were chosensince this cell type has been shown to be involved early inthe development of diabetic retinopathy.Methods: Peicytes were exposed to normal (5.5 mM) or high (22mM) glucose for 1, 3 and 5 days in a first series of experiments,and in the presence of hydrogen peroxide (0.1, 1.0, 5.0 micromol/L)or thiol reactive ions like mercury chloride (1, 10 micromol/L)in a second series of experiments. Signs of oxidative stresswere assessed by measuring expression of mRNA for the antioxidantenzymes CuZnSOD, MnSOD, catalase and glutathione peroxidasein the first series of experiments using real–time RT–PCR,and glutathione (GSH) concentrations in the second series ofexperiments using high–performance liquid chromatography.Lipid peroxidation was assessed by measuring the concentrationof malonedialdhyde using the BIOXYTECH LPO–586 colorimetricassay kit. Smooth muscle cells were used as positive control.Results: Despite stimulation with high glucose, hydrogen peroxideor thiol reactive metal ions, there was no clear increased expressionof anti–oxidative enzymes or influence on GSH levels.Under the same conditions, lipid peroxidation was increasedin bovine aortic smooth muscle cells but not in bovine retinalpericytes.Conclusions: Under the experimental conditions used, pericytesdo not develop oxidative stress in response to hyperglycemia.Thus, oxidative stress does not seem to be a major cause ofpericyte loss in the development of diabetic retinopathy.